Currently, Organic Light-emitting Diode (OLED) display devices have attracted attentions of the industry because of application advantages such as self-luminescence, no backlight module, light weight, thin thickness, simple structure and durability.
OLED devices have two types, i.e., a non-transparent type and a transparent type. Non-transparent OLED devices may only emit light on one side, therefore, in a case of preparing double-sided OLED display device, two independent display devices are required to be bonded, or substrates provided with OLED devices are required to be sealed respectively. Therefore, the cost of manufacturing a double-sided OLED display device by using non-transparent OLED devices is higher, and the thickness of the double-sided OLED display device is thicker. A transparent OLED device is capable of emitting light from double sides. A double-sided OLED display panel requires an anode and a cathode of an electroluminescent (EL) device have a higher transmittance. The anode is generally made of indium tin oxide (ITO), and the cathode may be made of indium zinc oxide (IZO) or Mg/Ag (9:1 thickness). EL devices emit light in both directions due to their self-luminescence properties, thereby realizing double-sided display of OLED devices. However, because the EL devices are transparent, environmental light may also pass through the OLED panel and exits together with self-emitted light of the EL devices; as a result, contrast of the OLED device is greatly reduced and use's viewing effect is influenced greatly by the environmental light.
Therefore, how to improve the contrast of double-sided OLED display device is a technical problem to be solved by a person having ordinary skill in the art.